A traffic jam in a city is a situation where cars want to move but cannot, usually because they are impeded by other cars. Sometimes, the cars are impeded by an obstacle, like a crashed car or a broken road. Other times, cars are impeded by other cars that are impeded by other cars that are impeded by the first set of cards, resulting in gridlock. Gridlock is particularly interesting because all the cars want to move, but none of them can move because they're arranged in a way that makes them all stuck.
A traffic jam in your brain is a situation where you have a lot of thoughts, all of which want to move, but none of them can move. Internally, this might feel like being yanked in many directions, some sort of mental stuttering or maybe running in circles really fast or maybe like you're a wounded animal. Noticing traffic jams is a precondition for being able to resolve them.
A traffic jam might look something like "I feel kind of tired, so many I should shower, but I'm planning on going to the gym later, so I want to shower after I go to the gym, but I want to eat before I go to the gym - oh that reminds me, I have to pay my friend back for the dinner they bought me yesterday - oh yeah, I also have to pay my credit card bill and cancel my netflix subscription and I really should watch the last few episodes of Television Show, but I can't because I have to write my thesis - oh man I'm so worried by my research isn't good enough and I want to solve a bigger problem so I can impress my mentor and..."
Related concepts are decision paralysis and thrashing.
How do you stop a traffic jam? The zeroth step is to figure out you're in a traffic jam. I've listed some of my/others phenomenology above; try and find your own.
The first step is to get a piece of paper/some computational device and brain dump everything that you want/are thinking/feeling. It is absolutely critical that the thing that you put the stuff onto isn't your brain. Note that you're not trying to generate a list of things that you should do, you're just trying to catalog all the things that you already want to do that are floating around in your brain.
For instance, a list for for the above might look something like:
It's critical that you dump everything that's currently on your mind so you have space to think about it. I gave one of my friends this exercise and they ended up writing down more that 50 things. 50! How do you even form coherent thoughts when there are 50 things in your brain constantly sapping your attention and working memory?
The second step is to clarify what the items on the list mean. Most of the items are straight forward TODOs, but "what if my research is bad and I'm bad" might benefit from a bit of focusing. Additionally, "so tired..." could be turned into "take a nap."
After clarifying, the list might look like:
The third step is to get real. Sometimes, you can't do all of the things that you want to do. There are generally two ways that this can be done:
The first way is to prune an item off your list and spend a few moments grieving the want that will not ever be satisfied. This process can really hurt. In the extreme case, this can involve realizing that you'll never be good at something that you've wanted for a while, simply because you know you'll never be able to find the time. I recently realized that I would probably never be able to write a good novel, which was painful.
The second way is to notice that some of the things you want are really hard and decide whether it's worth trying. There is an inherent tension in wanting something that is hard to get because the more you want it, the more painful it will be if you fail. It is important for the choice to be a genuine choice. There's a failure mode where you always try to do the hard things because that's what it seems like the protagonist is supposed to do. Protagonists have mental fortitude above those of ordinary humans; sometimes failure hurts too much and it's not worth it.
The imaginary person that has the above list can plausibly do everything on their list within the day except for "write thesis" and "solve big research problem". The first one probably needs to get done eventually, but maybe not at this moment, so they can prune it and grieve a little. The second one probably needs the imaginary person to decide whether or not it's worth trying to find a bigger problem to solve. Importantly, however, they don't have to decide right then as to what they want to do. Delay is slightly costly, but not delaying is often even more costly.
It is important, however, that you actually have a system in place for being able to reliably come back to deciding whether or not you want to try to find a bigger problem. Goal factoring might be a useful technique to try on decisions like these ones.
The last step is to make a plan to do all the things on your list.
After getting real, the list might look like:
So you might make a plan like:
Importantly, plans can be recursive. For instance, a different plan could be:
This step is probably the easier step. Remember to murphyjitsu your plan.
Get a piece of paper and brain dump everything that's floating around in your brain. My guess is that if you don't have reliable systems for capturing already, there will be a non-trivial amount of stuff floating around.
The get real with respect to the list you have and make a plan to do the rest.